Radiator caps for automobiles are known which are equipped with spaced members for seating against upstream and downstream seats provided on the filler neck of the radiator, with the lower member normally biased so as to effect a sealing force against the downstream seat, to seal the radiator and to cause the radiator to function at a selected design pressure above atmospheric pressure. When pressure in the radiator exceeds the selected design pressure, the lower seal member unseats to permit escape of pressurized gas and liquid and to avoid damage to the system. However, since some pressure is retained in the radiator, and since sudden release of the design pressure could itself be dangerous, it has been known to provide such a cap with means that compel release of all radiator pressure above atmospheric pressure before the cap can be removed from the radiator filler neck. In one such construction the lower member is provided with a vent valve that is selectively openable to release excess pressure, and is automatically openable to relieve a vacuum in the radiator. In another such construction, selective release of excess pressure is achieved by lifting the entire lower valve.
It is also known to provide a coolant recovery system for automotive radiators wherein the cap therefor includes a lower seal disc that is normally spring biased against the lower seat of a radiator's filler neck, such that as the raditor's coolant expands it operates to lift the lower seal disc to permit expanded coolant liquid to flow from the radiator to a coolant recovery container, and to then siphon back to the radiator upon the radiator cooling. The cap for such a system does not have means for selectively and safely venting excess pressure from the radiator. Thus, in coolant recovery systems, removal of a radiator cap before pressure in the radiator has been safely reduced, has led to hand burns; the alternative being substantial time delay in waiting for the radiator's contents to cool to a safe temperature.
Heretofore, no cap for a coolant recovery system has been provided with a safety venting valve feature which precludes removal of the cap until after radiator pressure had been released, and which also provides utility in the coolant recovery system permitting expanded coolant to flow to a coolant recovery container and providing for siphonage of coolant through the safety venting valve of the cap from the recovery container to the radiator upon cooling of the radiator.
It is desirable that a radiator cap prevent loss of radiator coolant liquid. However, wherever there exists a movable part that is required to act freely and easily in the presence of pressurized liquid, there always exists the possibility of undesirable leakage of liquid through the channels defined between moving parts.
Thus, one object of this invention is to provide a radiator cap for a coolant recovery system that provides both a safety venting feature which precludes removal of said cap until radiator pressure has been first vented to the coolant recovery reservoir and which also provides utility in the coolant recovery system, permitting passage of expanded coolant therepast to a coolant recovery container and which provides for siphonage of coolant from the recovery container through a portion of said radiator cap back into the radiator without loss of coolant past the cap.
Another object of this invention is to provide a multiple purpose radiator cap with a selectively movable stem for actuating a vent valve in the cap and with means to permit ready action of the movable stem while limiting leakage of pressurized liquid, and atmospheric air when siphoning, therethrough.
Further objects and advantages will become apparent to one skilled in the art from the following description of a preferred embodiment of the invention.